DIPAC2011 - List of Authors (Lefevre, T.)

Paper

Title

Page

The LHC Beam Position System: Performance during 2010 and Outlook for 2011

323

E. Calvo Giraldo, J.L. Gonzalez, L.K. Jensen, O.R. Jones, T. Lefèvre, J.-J. Savioz, R.J. Steinhagen, J. Wenninger
CERN, Geneva, Switzerland

This paper presents the performance of the LHC Beam Position System during 2010. The system proved to meet most specifications, was highly reliable and continuously provided 25Hz real-time orbit data with micron level resolution to the automatic global orbit feedback system. However, several issues were observed and they will be discussed in detail, such as the dependence on bunch intensity and the effect of surface electronics temperature variations on the measured position.

TUPD49

Performance of Parabolic and Diffusive OTR Screens at the CLIC Test Facility 3

413

M. Olvegård, B. Bolzon, E. Bravin, S. Burger, A.E. Dabrowski, T. Lefèvre
CERN, Geneva, Switzerland
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

At the CLIC Test Facility 3, OTR screens are commonly used in beam imaging systems for energy and energy spread characterization in dedicated spectrometer lines. In these lines the horizontal beam size is typically of the order of one centimeter. Already in 2005 a limitation was observed resulting from a strong dependence of the intensity of the light captured by the camera, on the position on the screen (vignetting). The severity of this effect increases with the electron energy, as the aperture of the optical system is finite and the OTR photons are emitted in a small cone of 1/γ angle. To mitigate this effect, different shapes and surface polishing of the screens were investigated. Parabolic and diffusive OTR radiators were tested in several spectrometer lines all along the CTF3 complex. The results are presented in this paper.

TUPD55

Performance of the Time Resolved Spectrometer for the 5 MeV Photo-Injector PHIN

431

D. Egger
EPFL, Lausanne, Switzerland
A.E. Dabrowski, M. Divall Csatari, S. Döbert, D. Egger, T. Lefèvre, Ö. Mete, M. Olvegård, M. Petrarca
CERN, Geneva, Switzerland

The PHIN photo-injector test facility is being commissioned at CERN in order to fulfill the beam parameter requirements for the 3rd CLIC Test Facility (CTF3), which includes the production of a 3.5 Amp stable beam, bunched at 1.5 GHz with a relative energy spread of less than 1%. A 90° spectrometer is instrumented with an OTR screen coupled to a gated intensified camera, followed by a segmented beam dump for time resolved energy measurements. The following paper describes the transverse and temporal resolution of the instrumentation with an outlook towards single-bunch energy measurements.

Poster TUPD55 [0.959 MB]

WEOA04

Synchrotron Radiation Measurements at the CERN LHC

550

F. Roncarolo, S. Bart Pedersen, A. Boccardi, E. Bravin, A. Guerrero, A. Jeff, T. Lefèvre, A. Rabiller
CERN, Geneva, Switzerland
A.S. Fisher
SLAC, Menlo Park, California, USA

The CERN LHC is equipped with two systems (one for each beam) designed to image the synchrotron radiation emitted by protons and heavy ions. After their commissioning in 2009, the detectors were extensively used and studied during the 2010 run. This allowed preliminary limits in terms of sensitivity, accuracy and resolution to be established. The upgrade to an intensified video camera capable of gating down to 25ns permitted the acquisition of single bunch profiles even with an LHC proton pilot bunch (~5·10⁹ protons) at 450 GeV or a single lead ion bunch (~10⁸ ions) from about 2 TeV. Plans for the optimization and upgrade of the system will be discussed. Since few months, part of the extracted light is deviated to the novel Longitudinal Density Monitor (LDM), consisting in an avalanche photo-diode detector providing a resolution better than 100 ps. The LDM system description will be complemented with the promising first measurement results.

Slides WEOA04 [6.398 MB]

Paper	Title	Page
TUPD12	The LHC Beam Position System: Performance during 2010 and Outlook for 2011	323
	E. Calvo Giraldo, J.L. Gonzalez, L.K. Jensen, O.R. Jones, T. Lefèvre, J.-J. Savioz, R.J. Steinhagen, J. Wenninger CERN, Geneva, Switzerland
	This paper presents the performance of the LHC Beam Position System during 2010. The system proved to meet most specifications, was highly reliable and continuously provided 25Hz real-time orbit data with micron level resolution to the automatic global orbit feedback system. However, several issues were observed and they will be discussed in detail, such as the dependence on bunch intensity and the effect of surface electronics temperature variations on the measured position.

TUPD49	Performance of Parabolic and Diffusive OTR Screens at the CLIC Test Facility 3	413
	M. Olvegård, B. Bolzon, E. Bravin, S. Burger, A.E. Dabrowski, T. Lefèvre CERN, Geneva, Switzerland C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	At the CLIC Test Facility 3, OTR screens are commonly used in beam imaging systems for energy and energy spread characterization in dedicated spectrometer lines. In these lines the horizontal beam size is typically of the order of one centimeter. Already in 2005 a limitation was observed resulting from a strong dependence of the intensity of the light captured by the camera, on the position on the screen (vignetting). The severity of this effect increases with the electron energy, as the aperture of the optical system is finite and the OTR photons are emitted in a small cone of 1/γ angle. To mitigate this effect, different shapes and surface polishing of the screens were investigated. Parabolic and diffusive OTR radiators were tested in several spectrometer lines all along the CTF3 complex. The results are presented in this paper.

TUPD55	Performance of the Time Resolved Spectrometer for the 5 MeV Photo-Injector PHIN	431
	D. Egger EPFL, Lausanne, Switzerland A.E. Dabrowski, M. Divall Csatari, S. Döbert, D. Egger, T. Lefèvre, Ö. Mete, M. Olvegård, M. Petrarca CERN, Geneva, Switzerland
	The PHIN photo-injector test facility is being commissioned at CERN in order to fulfill the beam parameter requirements for the 3rd CLIC Test Facility (CTF3), which includes the production of a 3.5 Amp stable beam, bunched at 1.5 GHz with a relative energy spread of less than 1%. A 90° spectrometer is instrumented with an OTR screen coupled to a gated intensified camera, followed by a segmented beam dump for time resolved energy measurements. The following paper describes the transverse and temporal resolution of the instrumentation with an outlook towards single-bunch energy measurements.
	Poster TUPD55 [0.959 MB]

WEOA04	Synchrotron Radiation Measurements at the CERN LHC	550
	F. Roncarolo, S. Bart Pedersen, A. Boccardi, E. Bravin, A. Guerrero, A. Jeff, T. Lefèvre, A. Rabiller CERN, Geneva, Switzerland A.S. Fisher SLAC, Menlo Park, California, USA
	The CERN LHC is equipped with two systems (one for each beam) designed to image the synchrotron radiation emitted by protons and heavy ions. After their commissioning in 2009, the detectors were extensively used and studied during the 2010 run. This allowed preliminary limits in terms of sensitivity, accuracy and resolution to be established. The upgrade to an intensified video camera capable of gating down to 25ns permitted the acquisition of single bunch profiles even with an LHC proton pilot bunch (~5·10⁹ protons) at 450 GeV or a single lead ion bunch (~10⁸ ions) from about 2 TeV. Plans for the optimization and upgrade of the system will be discussed. Since few months, part of the extracted light is deviated to the novel Longitudinal Density Monitor (LDM), consisting in an avalanche photo-diode detector providing a resolution better than 100 ps. The LDM system description will be complemented with the promising first measurement results.
	Slides WEOA04 [6.398 MB]